Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-18T18:45:59+00:00	DMARC	—	VALID	`69808cc65e20…`
2026-08-18T18:45:59+00:00	SPF	—	VALID	`f1e731c738d6…`